d19 Low

Alpha d19 Fault Code

Also written as D19 — same fault.

The Alpha d19 fault code means: your boiler is displaying an internal software diagnostic screen, which usually means the system is performing a self-check or has encountered a minor glitch in its display settings.. It appears on 5 Alpha models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Toggles between safety software version / functional software version n/a
Typical repair cost £80-150 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Alpha models that show the d19 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Alpha d19 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026